Integrated drying and gasification process for simultaneously producing synthetic gas and high rank coal

Abstract

The present invention relates to a gasification process for efficiently co-producing synthesis gas and high-grade coal from water-containing coal, and to an integrated drying and gasification system for realizing the same.

What is claimed is: 
     
       1. A gasification method of co-producing synthesis gas and high-quality coal, comprising the steps of:
 a) supplying low-quality water-containing coal to a dryer; 
 b) drying the low-quality water-containing coal in the dryer, in which thermal energy necessary for drying the low-quality water-containing coal is supplied in contact with synthesis gas recycled to the dryer from a gasification step; 
 c) separating dried coal and synthesis gas discharged from the dryer using solid-gas separation and then recovering the separated synthesis gas; 
 d) transferring target amounts of the separated dried coal to a gasifier in a fluidic state using a loop seal type transfer means to which aeration gas is supplied by a plurality of ports and simultaneously recovering a high-quality dried coal which is not transferred to the gasifier; 
 e) gasifying the transferred dried coal in the gasifier to prepare synthesis gas; and 
 f) directly recycling the synthesis gas of 400 to 1500° C. discharged from the gasifier without passing the synthesis gas through a heat exchanger(s), 
 wherein the dryer provides a drying capacity necessary for producing the dried coal separated and recovered from the low-quality water-containing coal and the dried coal transferred to the gasification step. 
 
     
     
       2. The gasification method of  claim 1 , wherein the content of water in the low-quality water-containing coal is 10 to 70 wt %. 
     
     
       3. The gasification method of  claim 1 , wherein the dried coal has a water content of 10 wt % or less. 
     
     
       4. The gasification method of  claim 1 , wherein the low-quality water-containing coal is pulverized to a particle size of 50 to 6000 μm and then introduced into the dryer, before the step a). 
     
     
       5. The gasification method of  claim 1 , wherein the content of carbon in the low-quality water-containing coal is at least 20 wt %. 
     
     
       6. The gasification method of  claim 1 , wherein the dryer is a pneumatic or flash dryer, a fluidized-bed dryer, a rotary dryer or a rotary tube dryer. 
     
     
       7. The gasification method of  claim 6 , wherein the dryer is a pneumatic or flash dryer. 
     
     
       8. The gasification method of  claim 1 , wherein the low-quality water-containing coal and synthesis gas are in contact with each other in a parallel stream in the dryer. 
     
     
       9. The gasification method of  claim 1 , wherein the operating pressure in the dryer is 60 kg/cm 2  or less, the operating temperature at an inlet of the dryer is adjusted in a range of 400 to 1500° C., and the operating temperature at an outlet of the dryer is adjusted in a range of 200 to 700° ° C. 
     
     
       10. The gasification method of  claim 1 , further comprising the step of forming the dried coal separated and recovered in the step d) into pellets, briquettes or granules. 
     
     
       11. The gasification method of  claim 1 , the aeration gas is nitrogen, carbon dioxide, steam, synthesis gas generated from the gasifier, or a mixture thereof. 
     
     
       12. The gasification method of  claim 1 , wherein the operating temperature in the gasifier is 400 to 1500° C., and the operating pressure in the gasifier is 1 to 60 kg/cm 2 . 
     
     
       13. The gasification method of  claim 1 , wherein, in the step e), the molar ratio of O 2 /C is 0.1 to 1.0, and the molar ratio of CO 2 /C is 0 to 1. 
     
     
       14. The gasification method of  claim 1 , wherein, in the step e), the molar ratio of steam/C is 0 to 2. 
     
     
       15. The gasification method of  claim 1 , wherein the weight ratio of synthesis gas recycled to the dryer in the step b): low-quality water-containing coal is 1:1 to 10:1. 
     
     
       16. The gasification method of  claim 1 , wherein the weight ratio of dried coal separated and recovered in the step d): dried coal transferred to the gasifier is 1:1 to 4:1. 
     
     
       17. The gasification method of  claim 1 , further comprising the step of separating and recovering tar generated in the step of drying the low-quality water-containing coal and included in the synthesis gas in the step c) of recovering the synthesis gas. 
     
     
       18. The gasification method of  claim 17 , wherein the dryer provides a heat capacity larger than a drying capacity necessary for producing the dried coal separated and recovered from the low-quality water-containing coal and the dried coal transferred to the gasification step.